This invention relates to new and useful compositions of matter classifiable in the field of organic chemistry as derivatives of dibenzthiepins. More particularly, the instant invention relates to a novel group of dibenz[b,f]thiepins having a fourth ring of five or six carbon atoms, fused to the main ring system e.g., benz[b]indeno[f]thiepins; to methods of preparing such compounds; and to the method of employing them in the treatment and control of allergic conditions such as asthma.